How Do I Get Theme On My Phone? Help!

I have a blackberry pearl 8120, i have found themes and downloaded them to my computer, then i plug my phone up to my computer, get on blackberry device manager, then go to application loader, click add device an in my downloads file i have to click all folder because it show nothing is there that is *.alx or *.ali, but once i click on all folders then my themes show up, i click on one, a box then pops up that says error in application information file "C:\users\haley\downloads\luminescense2-81.zip" there is an XML syntax error on line 1, i click ok then a box pops up saying no additional applications designed for your device were found.